It's a commission for access to a lucrative market that Apple created. Apple gives away the developer tools and charges an extremely modest annual App Store fee, which also covers the review process and hosting. It's been common for platform creators to charge third-party developers in some capacity for many decades. Some do it by charging high costs for the developer tools, others by charging a commission based on sales. I don't think any strategy is necessarily better or worse than the other on a legal or moral basis; they're just business decisions. Previously Apple has combined the commission and payment processing costs into one fee. Apple made a decision on what they wanted to offer developers on that platform and Epic wasn't satisfied with it. They got a court to agree on what is ultimately a minor technical point in how Apple's deal is packaged so Apple is offering an alternative that they don't want to but complies with the law. It's, ultimately, a worse deal for the developer. Developers don't have a right to demand that some arbitrary percentage is the right one, tough. Apple offered a deal: take it or leave it. Developers are perfectly free to leave it.